Humidity detection circuit schematic diagram

This circuit diagram shows the circuit of a humidity detector. The sensor is composed of two sets of thin wires, each wire is very close to each other, about 2mm. When raindrops fall or the air humidity is high, two sets of wires form a wire path. The 6V power supply voltage is added to the base of transistor BG1 through resistor R1, causing BG1 to conduct. The voltage drop on R2 causes the thyristor to turn on. SCR1 is turned on and the alarm sends out an alarm signal. Only by turning off switch K can the alarm be stopped. Transistor BG1 is 2N3706, which can be replaced by domestic model 3DK9B.